Test Reatta gets over 60 MPG

[Guest allbuick]

In a recent test that had an 89 Reatta accumulate over 1000 miles, at speeds of between 60 and 122 mph, with an average speed 87 mph, even with 150,000 plus miles on it, the total fuel consumption was 16.49 gallons resulting in mileage of just over 60 mpg.<BR>This test was performed on a chassis dyno that allowed for no aero drag, or friction from brakes. The partial purpose of the test was to see how the drivetrain could handle extended periods at high speed. Most of the testing was done in the 90 to 95 mph range. The only falure during this test was the inner axle boots. At high speeds (near 100 mph)the inner boots would begin to whip with the weight of the grease collecting in one side of the boot. After as little as 40 minutes the boot would split open and spray cv joint grease everywhere. What a mess that made all three times it happened. This failure did not occur nor did the condition even show at speeds below 90 mph.<BR>When the boot on the right side gave up, grease was slung into the belt and in conjuction with the air coming form the alternator fan covered everthing on that side with grease. On the left (drivers) side the boot failure was more controlled because the inner boot is covered by the transaxle and various components on the side. One concern did arise in that at these speeds the exhuast system would glow bright red almost down to the catalytic converter. The grease did find its way to the crossover pipe and there was a lot of smoke, but no fire. Of course, at real highway speeds the air traveling past the engine compartment at 100 mph, and the hood being close would have changed where the grease was sprayed. <BR>Other than axle boots there was no other concerns during this short test. <BR><p>[This message has been edited by allbuick (edited 12-18-2000).]

[Guest Stan Leslie]

While your 'experiment' is interesting, the only piece of relevant information I found was a possible explanation for boot failures. The mileage means nothing without knowing how the dyno load relates to a real world situation (sounds like almost not at all). As far as the exhaust temps, same goes here. Actually a worse condition than having load applied as no extra fuel enrichment is being applied at these very light loads. At higher speeds and loads the fuel enrichment will actually cool the exhaust.

[Guest]

Did you happen to take off the tires & brake assemblies too? I'm just curious ... and am feeling the need to be a little bit of a trouble maker today.<BR>~Brenda<P>------------------<BR>REATTA SITE:<A HREF="http://members.aol.com/gohighr/reatta.html" TARGET=_blank><BR>http://members.aol.com/gohighr/reatta.html</A>

[Guest]

Actually, since the vehicle didn't actually "go" anywhere, you got 0 mpg during your test. <BR>

[Guest allbuick]

Tire were removed after the second axle boot explosion so the situation could be monitored closer. Brakes were left on. The mileage that the odometer registered under the conditions really is not indicative in any way of anything as it relates to useable mpg numbers, just one of the things we noticed. Because there is a 91 Reatta headed for Germany the question surfaced of what speeds this car is capable of on the Autobahn. The a/c compressor survived, the power steering and auto trans did not aerate their fluids, and there were no drivetrain harmonic vibrations except just before the inner boots let loose. This whole thing is not in any way to suggest that these cars are designed for, or are safe, at those speeds. As noted this was not a highway test. Aerodynamics and stability were no issue tied down to a dyno. Once the tires were removed even the chassis rollers became useless and the whole drivetrain freewheeled. Perhaps one of the worst things you can do to one is let it operate at those kinds of speeds with no load for hour after hour.